Reading device and reading method for fingerprint sensor

Abstract

A reading device and a reading method for a fingerprint sensor are provided. The reading device includes a switching circuit, a plurality of analog front end (AFE) circuits and a calculation circuit. The switching circuit is coupled to a plurality of pixel units of the fingerprint sensor. The AFE circuits are coupled to the switching circuit. The calculation circuit is coupled to the AFE circuits for calculating a plurality of pixel data of the pixel units. For a first pixel unit among the pixel units, the calculation circuit reads the first pixel unit by using different AFE circuits among the AFE circuits, so as to obtain a plurality of first original sensing values of the first pixel unit. The calculation circuit calculates the pixel data of the first pixel unit according to the plurality of first original sensing values.

What is claimed is: 
     
       1. A reading device for a fingerprint sensor, comprising:
 a switching circuit, coupled to a plurality of pixel units of the fingerprint sensor; 
 a plurality of analog front end (AFE) circuits, coupled to the switching circuit; and 
 a calculation circuit, coupled to the AFE circuits, and configured to calculate a plurality of pixel data of the pixel units, wherein for a first pixel unit among the pixel units, the calculation circuit reads the first pixel unit by using different AFE circuits among the AFE circuits, so as to obtain a plurality of first original sensing values of the first pixel unit, and calculates the pixel data of the first pixel unit by using the plurality of first original sensing values. 
 
     
     
       2. The reading device according to  claim 1 , wherein the calculation circuit calculates an average value of the plurality of first original sensing values to serve it as the pixel data of the first pixel unit. 
     
     
       3. The reading device according to  claim 1 , wherein the AFE circuits comprises a first AFE circuit, a second AFE circuit, a third AFE circuit and a fourth AFE circuit; the pixel units comprises the first pixel unit, a second pixel unit, a third pixel unit and a fourth pixel unit;
 at a first time, the calculation circuit reads the first pixel unit, the second pixel unit, the third pixel unit and the fourth pixel unit respectively by using the first AFE circuit, the second AFE circuit, the third AFE circuit and the fourth AFE circuit to obtain a first sensing value, a second sensing value, a third sensing value and a fourth sensing value; 
 at a second time, the calculation circuit reads the first pixel unit, the second pixel unit, the third pixel unit and the fourth pixel unit respectively by using the second AFE circuit, the third AFE circuit, the fourth AFE circuit and the first AFE circuit to obtain a fifth sensing value, a sixth sensing value, a seventh sensing value and an eighth sensing value; 
 at a third time, the calculation circuit reads the first pixel unit, the second pixel unit, the third pixel unit and the fourth pixel unit respectively by using the third AFE circuit, the fourth AFE circuit, the first AFE circuit and the second AFE circuit to obtain a ninth sensing value, a tenth sensing value, an eleventh sensing value and a twelfth sensing value; and 
 at a fourth time, the calculation circuit reads the first pixel unit, the second pixel unit, the third pixel unit and the fourth pixel unit respectively by using the fourth AFE circuit, the first AFE circuit, the second AFE circuit and the third AFE circuit to obtain a thirteenth sensing value, a fourteenth sensing value, a fifteenth sensing value and a sixteenth sensing value. 
 
     
     
       4. The reading device according to  claim 3 , wherein the calculation circuit calculates an average value of the first sensing value, the fifth sensing value, the ninth sensing value and the thirteenth sensing value to serve it as the pixel data of the first pixel unit, calculates an average value of the second sensing value, the sixth sensing value, the tenth sensing value and the fourteenth sensing value to serve it as the pixel data of the second pixel unit, calculates an average value of the third sensing value, the seventh sensing value, the eleventh sensing value and the fifteenth sensing value to serve it as the pixel data of the third pixel unit, and calculates an average value of the fourth sensing value, the eighth sensing value, the twelfth sensing value and the sixteenth sensing value to serve it as the pixel data of the fourth pixel unit. 
     
     
       5. A reading method for a fingerprint sensor, comprising:
 disposing a switching circuit, wherein the switching circuit is coupled to a plurality of pixel units of the fingerprint sensor; 
 disposing a plurality of analog front end (AFE) circuits, wherein the AFE circuits are coupled to the switching circuit; 
 disposing a calculation circuit, wherein the calculation circuit is coupled to the AFE circuits; 
 reading a first pixel unit among the pixel units by using different AFE circuits among the AFE circuits by the calculation circuit, so as to obtain a plurality of first original sensing values of the first pixel unit; and 
 calculating a pixel data of the first pixel unit according to the plurality of first original sensing values by the calculation circuit. 
 
     
     
       6. The reading method according to  claim 5 , wherein the step of calculating the pixel data of the first pixel unit comprises:
 calculating an average value of the plurality of first original sensing values to serve it as the pixel data of the first pixel unit by the calculation circuit. 
 
     
     
       7. The reading method according to  claim 5 , further comprising:
 reading the first pixel unit by using a first AFE circuit among the AFE circuits to obtain a first sensing value at a first time by the calculation circuit; 
 reading a second pixel unit among the pixel units by using a second AFE circuit among the AFE circuits to obtain a second sensing value at the first time by the calculation circuit; 
 reading a third pixel unit among the pixel units by using a third AFE circuit among the AFE circuits to obtain a third sensing value at the first time by the calculation circuit; 
 reading a fourth pixel unit among the pixel units by using a fourth AFE circuit among the AFE circuits to obtain a fourth sensing value at the first time by the calculation circuit; 
 reading the first pixel unit by using the second AFE circuit to obtain a fifth sensing value at a second time by the calculation circuit; 
 reading the second pixel unit by using the third AFE circuit to obtain a sixth sensing value at the second time by the calculation circuit; 
 reading the third pixel unit by using the fourth AFE circuit to obtain a seventh sensing value at the second time by the calculation circuit; 
 reading the fourth pixel unit by using the first AFE circuit to obtain an eighth sensing value at the second time by the calculation circuit; 
 reading the first pixel unit by using the third AFE circuit to obtain a ninth sensing value at a third time by the calculation circuit; 
 reading the second pixel unit by using the fourth AFE circuit to obtain a tenth sensing value at the third time by the calculation circuit; 
 reading the third pixel unit by using the first AFE circuit to obtain an eleventh sensing value at the third time by the calculation circuit; 
 reading the fourth pixel unit by using the second AFE circuit to obtain a twelfth sensing value at the third time by the calculation circuit; 
 reading the first pixel unit by using the fourth AFE circuit to obtain a thirteenth sensing value at a fourth time by the calculation circuit; 
 reading the second pixel unit by using the first AFE circuit to obtain a fourteenth sensing value at the fourth time by the calculation circuit; 
 reading the third pixel unit by using the second AFE circuit to obtain a fifteenth sensing value at the fourth time by the calculation circuit; and 
 reading the fourth pixel unit by using the third AFE circuit to obtain a sixteenth sensing value at the fourth time by the calculation circuit. 
 
     
     
       8. The reading method according to  claim 7 , further comprising:
 calculating an average value of the first sensing value, the fifth sensing value, the ninth sensing value and the thirteenth sensing value to serve it as the pixel data of the first pixel unit by the calculation circuit; 
 calculating an average value of the second sensing value, the sixth sensing value, the tenth sensing value and the fourteenth sensing value to serve it as a pixel data of the second pixel unit by the calculation circuit; 
 calculating an average value of the third sensing value, the seventh sensing value, the eleventh sensing value and the fifteenth sensing value to serve it as a pixel data of the third pixel unit by the calculation circuit; and 
 
       calculating an average value of the fourth sensing value, the eighth sensing value, the twelfth sensing value and the sixteenth sensing value to serve it as a pixel data of the fourth pixel unit by the calculation circuit.